Bevy 3d Materials Agent Skill

Bevy 3D materials

When to use

Load this when a mesh needs a PBR surface. Custom shader extension points are on bevy-shaders. Lighting is on bevy-3d-lighting.

ECS shape

• Type: StandardMaterial (feature blurbs and DistanceFog).
• Extension: ExtendedMaterial on the pbr page.
• Features that mention StandardMaterial textures: pbr_anisotropy_texture, pbr_multi_layer_material_textures, pbr_specular_textures, pbr_transmission_textures. Check the struct page for field names before writing them.
• Plugin: bevy_pbr adds PBR rendering. It is part of the 3d render collection.

Surface choice

| Need | Bevy idiom |

| --- | --- |

| PBR surface | StandardMaterial on MeshMaterial3d, with base_color, metallic, and perceptual_roughness. |

| Extra shader data on that surface | ExtendedMaterial<StandardMaterial, E> where E: MaterialExtension. |

| Transparency | alpha_mode: AlphaMode::Mask for cutout, AlphaMode::Blend for glass. |

Examples

[dependencies]
bevy = "0.20"

Spawn a mesh with a metal StandardMaterial. The mesh component is Mesh3d. The material component is MeshMaterial3d<StandardMaterial>.

fn spawn_metal(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    let mesh = meshes.add(Cuboid::new(1.0, 1.0, 1.0));
    let material = materials.add(StandardMaterial {
        base_color: Color::srgb(0.75, 0.15, 0.12),
        metallic: 1.0,
        perceptual_roughness: 0.25,
        reflectance: 0.5,
        ..default()
    });
    commands.spawn((Mesh3d(mesh), MeshMaterial3d(material), Transform::default()));
}

Cutout foliage discards fragments under the mask. Glass uses alpha blending and a translucent base color.

fn cutout_leaf(image: Handle<Image>) -> StandardMaterial {
    StandardMaterial {
        base_color_texture: Some(image),
        alpha_mode: AlphaMode::Mask(0.5),
        diffuse_transmission: 0.4,
        cull_mode: None,
        ..default()
    }
}

fn glass() -> StandardMaterial {
    StandardMaterial {
        base_color: Color::srgba(0.7, 0.85, 1.0, 0.25),
        alpha_mode: AlphaMode::Blend,
        metallic: 0.0,
        perceptual_roughness: 0.05,
        ..default()
    }
}

One shared asset stays the source of truth. A runtime tint clones the handle's material into a new asset so other meshes keep the original.

fn tint_one_mesh(
    mut materials: ResMut<Assets<StandardMaterial>>,
    mesh: Query<&MeshMaterial3d<StandardMaterial>>,
) {
    let Ok(handle) = mesh.single() else {
        return;
    };
    let Some(source) = materials.get(handle.id()) else {
        return;
    };
    let mut tinted = source.clone();
    tinted.base_color = Color::srgb(0.2, 0.45, 0.9);
    let _unique = materials.add(tinted);
}

ExtendedMaterial keeps every StandardMaterial field and adds extension data. Register the concrete material type before spawning it.

use bevy::pbr::{ExtendedMaterial, MaterialExtension};
use bevy::render::render_resource::AsBindGroup;

#[derive(Asset, AsBindGroup, TypePath, Clone, Default)]
struct Wear {
    #[uniform(100)]
    amount: f32,
}

impl MaterialExtension for Wear {}

fn register_wear(app: &mut App) {
    app.add_plugins(MaterialPlugin::<ExtendedMaterial<StandardMaterial, Wear>>::default());
}

fn spawn_worn(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<ExtendedMaterial<StandardMaterial, Wear>>>,
) {
    let mesh = meshes.add(Cuboid::new(1.0, 1.0, 1.0));
    let material = materials.add(ExtendedMaterial {
        base: StandardMaterial {
            base_color: Color::srgb(0.4, 0.35, 0.3),
            perceptual_roughness: 0.8,
            ..default()
        },
        extension: Wear { amount: 0.6 },
    });
    commands.spawn((Mesh3d(mesh), MeshMaterial3d(material)));
}

Expert Knowledge Delta

Target: Bevy 0.20+.

Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.

Who owns state

| Piece | Owner | Who may mutate | Schedule |

| --- | --- | --- | --- |

| Data on one entity | Component | One system via Query | Update or FixedMain |

| One value for the whole app | Resource | One system | Startup to insert, then the schedule that reads it |

| Spawn | Commands | The spawning system | Startup for the initial world; later schedules for runtime spawn |

| Order that must not race | .chain() | The chained systems only | Same schedule |

| Plugin boundary | Plugin | build registers systems and resources | Before the app runs |

Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.

Decision

| If you need | Do this | Do not |

| --- | --- | --- |

| Per-entity data | Component + Query | A plain struct stored outside the world |

| App-wide config or clock | Resource | Copy the value onto every entity |

| Stable simulation step | FixedMain and the Fixed clock | Tie simulation to raw frame Update |

| Startup spawn | Commands in Startup | Spawn from a render system |

| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging | A new event type invented in this file |

| An API outside the documented set | Check the official docs first | A made-up crate or API |

Load references/ecs-ownership.md for the ownership table.

NEVER

• Do not pin /0.20.0/ in docs URLs. WHY: links stay on latest; the 0.20 target is stated once in prose.
• Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless .chain() orders them.
• Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.

• No material fields this skill did not name. WHY: unnamed fields change between Bevy releases and the compiler is the check.
• No invented APIs or unnamed third-party crates as the chosen solver. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.

Reference

The library pin on bevy-master stays 0.20.0. Permalinks stay unversioned.

Official Documentation

• Assets - Official asset catalog. No third-party crate was selected.
• Examples - Example tree on the latest branch.
• 3D examples - Mesh, material, and lighting samples.
• ECS - Component, systems, Query, Startup, Update, and .chain().
• Plugins - Plugin, DefaultPlugins, MinimalPlugins, and add_plugins.

Related Skills

Prerequisites

• bevy-master - Hub and schedules.
• bevy-ecs-composition - Components and systems.
• bevy-shaders - Custom shaders and material extensions.
• bevy-3d-lighting - Lights that shade the material.

Complements

• None yet.

Downstream / consumers

• None yet.

Master

• bevy-master - Bevy router.